CAMBRIDGE, Mass.--(BUSINESS WIRE)--Nov. 20, 2007 - Vertex
Pharmaceuticals Incorporated (Nasdaq: VRTX) and Merck & Co.,
Inc. today provided an update to their collaborative Aurora kinase
research and development program, which is targeting the treatment
of cancer. Merck has suspended enrollment in clinical trials of the
lead investigational Aurora kinase inhibitor in the collaboration,
MK-0457 (VX-680), pending a full analysis of all efficacy and
safety data for MK-0457. The decision was based on preliminary
safety data, in which a clinical safety finding of QTc prolongation
was observed in one patient. Merck and Vertex have a broad research
and development program underway to evaluate Aurora kinase
inhibitors as novel approaches to targeted cancer treatment. As
part of Merck's strategy to develop multiple drug candidates in
different tumor types and treatment combinations, Merck plans to
initiate in early 2008 a Phase 1 trial of VX-689 in patients with
advanced and/or refractory solid tumors.

MK-0457 is being investigated in a Phase 2 trial in patients
with treatment-refractory chronic myelogenous leukemia (CML) or
Philadelphia chromosome-positive acute lymphoblastic leukemia
(Ph+ALL) containing the T315I mutation, as well as an ongoing Phase
1 clinical trial in patients with advanced leukemias. Patients
currently enrolled in these trials may continue to be treated with
MK-0457, with additional monitoring for QTc prolongation. A
recently initiated Phase 1 trial of MK-0457 in combination with
dasatinib in patients with CML or Ph+ALL has also been suspended.
In addition, development of the Aurora kinase inhibitor MK-6592
(VX-667) has been discontinued after the compound did not meet
pharmacokinetic objectives in a Phase 1 clinical study.

About Merck Oncology

Merck Oncology focuses on all aspects of cancer care --
prevention, treatment, and supportive care. Through strong internal
research capabilities, selective alliances and acquisitions, and
enabling technologies such as the Molecular Profiling platform of
Rosetta, Merck Oncology is looking to lead in the discovery,
development and delivery of targeted anticancer therapies
customized for patient subpopulations. Merck Oncology conducts
research at sites in Boston, Seattle, West Point, Japan and
Italy.

About Vertex

Vertex Pharmaceuticals Incorporated is a global biotechnology
company committed to the discovery and development of breakthrough
small molecule drugs for serious diseases. The Company's strategy
is to commercialize its products both independently and in
collaboration with major pharmaceutical companies. Vertex's product
pipeline is focused on viral diseases, inflammation, autoimmune
diseases, cancer, pain and bacterial infection. Vertex
co-discovered the HIV protease inhibitor, Lexiva, with
GlaxoSmithKline. Vertex's press releases are available at
www.vrtx.com.

Lexiva is a registered trademark of the GlaxoSmithKline group of
companies.

Safe Harbor Statement

This press release may contain forward-looking statements,
including statements that (i) Merck and Vertex expect to continue
to evaluate the clinical potential of Aurora kinase inhibitors,
with the goal of developing multiple drug candidates in different
tumor types and treatment combinations, and (ii) Merck expects to
initiate a Phase 1 clinical trial of VX-689 in early 2008. While
management makes its best efforts to be accurate in making
forward-looking statements, such statements are subject to risks
and uncertainties that could cause the actual results of studies to
vary materially. Those risks and uncertainties include, among other
things, the risk that planned studies will not be commenced due to
unanticipated scientific developments or business constraints, that
observed outcomes in clinical investigations of smaller numbers of
patients will not be reflected in clinical trials involving larger
numbers of patients, that unexpected and adverse outcomes in
ongoing clinical and nonclinical studies will occur, and other
risks listed under Risk Factors in Vertex's Form 10-K filed with
the Securities and Exchange Commission on March 1, 2007. Vertex
disclaims any obligation to update the information contained in
this press release as new data become available.